Image guided medical and surgical procedures utilize patient images obtained prior to or during a medical procedure to guide a physician performing the procedure. Recent advances in imaging technology, especially in imaging technologies that produce highly-detailed, computer-generated two, three and four-dimensional images, such as computed tomography (CT), magnetic resonance imaging (MRI), isocentric C-arm fluoroscopic imaging, fluoroscopes or ultrasounds have increased the interest in image guided medical procedures. During these image guided medical procedures, the area of interest of the patient that has been imaged is displayed on a display. Surgical instruments and/or implants that are used during this medical procedure are tracked and superimposed onto this display to show the location of the surgical instrument relative to the area of interest in the body.
Other types of navigation systems operate as an image-less system, where an image of the body is not captured by an imaging device prior to the medical procedure. With this type of procedure, the system may use a probe to contact certain landmarks in the body, such as landmarks on bone, where the system generates either a two-dimensional or three-dimensional model of the area of interest based upon these contacts. This way, when the surgical instrument or other object is tracked relative to this area, they can be superimposed on this model.
Most types of orthopedic medical procedures are performed using conventional surgical techniques. These techniques generally involve opening the patient in a relatively invasive manner to provide adequate viewing by the surgeon during the medical procedure. These types of procedures, however, generally extend the recovery period for the patient due to the extent of soft tissue and muscular incisions resulting from the medical procedure. Use of image guided technology in orthopedic medical procedures would enable a more minimally invasive type of procedure to be performed to thereby reduce the overall recovery time and cost of the procedure. Use of the image guided procedure may also enable more precise and accurate placement of an implant within the patient.
Once the implant has been surgically positioned within the patient, the patient's surrounding anatomy generally heals over time with the surrounding skeletal and muscular structure regaining a healthy state. However, since the implant is generally implanted when the patient is dysfunctional, this muscular and skeletal adjustment or healing may effect the subsequent range of motion, effectiveness, life expectancy of the implant, performance of the implant, and potentially cause deterioration of surround discs or implants. For example, in a spinal implant, upon the abdominal and back muscles strengthening after the implant procedure, the spine may subsequently align. This alignment may result in the implant or articulation faces of the implant being impinged because of the resultant alignment. This may result in a revision-type surgery that requires the implant to be removed and a subsequent implant being repositioned at the implant site.
The surgical procedures performed during orthopedic medical procedures, including spinal procedures, require the use of various instruments, assemblies and jigs to perform the procedure. Typically, jigs are used to support a single instrument that must be attached to the area of interest when the instrument is being used. Multiple jigs are thus typically required to be attached and removed from the area of interest as the procedure progresses. Use of multiple jigs and instruments, along with attaching and reattaching to the area of interest provides for a tedious and time consuming procedure. Moreover, inherent inaccuracies due to this procedure may provide less than acceptable results.
It is, therefore, desirable to provide a method and apparatus for post-operative adjustment or tuning of an implant, such as a spinal implant using telemetric or minimally invasive techniques. It is also desirable to provide an instrument assembly that may be attached to the implant site, such as a spinal implant site, once during the entire procedure, thereby reducing surgical time, costs, as well as increasing surgical accuracy. It is, therefore, an object of the present invention to provide such methods and apparatus for use in medical procedures.